SEED DORMANCY AND GERMINATION MECHANISMS IN EREMOPHILA (MYOPORACEAE)

Eremophila R.Br. (Myoporaceae) species are hardy perennial shrubs and trees which are endemic to Australia. They offer potential in revegeta tion and horticultural programmes and are currently propagated from cu ttings, since they have proven difficult to grow from fruits. Fruits o f E. maculata (Ker Gawl.) F.Muell. contain multiple seeds, and potenti al seed viability decreases from 58-74% over the first 3 years to 8% a fter 10 years. Up to 98% germination is obtained with seeds of E. macu lata excised from the fruit, compared to 28% germination from the frui t. Since older fruits, which are characterised by a weathered fruit ap ex, allow a greater number of seedlings to emerge during optimum condi tions, Eremophila germination appears to be controlled primarily by ph ysical dormancy due to the woody endocarp which surrounds the seeds. C hemical dormancy also plays an important role in the establishment of Eremophila, and germination inhibitors have been found within the frui t wall of E. maculata and E. racemosa (Endl.) F.Muell. The inhibitors from E. maculata appear to be water-soluble aromatic glycosides. It is suggested that germination in the field is triggered by leaching of t hese compounds from the fruit during intense precipitation.